Surface and volume coils are used in MRI imaging or spectroscopy procedures in order to obtain more accurate or detailed images of tissue under investigation. Preferably, a MRI coil performs accurate imaging or spectroscopy across a wide range of resonant frequencies, is easy to use, and is affordable. Further, the operating volume inside the main magnet of many MRI systems is relatively small, often just large enough for a patient's head or body. As a result, there is typically little space available for a coil in addition to the patient. Accordingly, it is advantageous if a surface or volume coil itself occupies as little space as possible.
In high fields (3 Tesla and beyond), due to the high Larmour frequencies required, radiation losses of RF coils become significant which decreases a coil's quality factor or Q factor, and a low Q factor can result in low signal-to-noise ratio (SNR) in MRI procedures. One existing solution to reducing radiation losses is adding a RF shielding around the coil(s). The RF shielding, however, usually makes the physical size of RF coil much larger, which as noted above is not desired in the MR studies, especially in the case of high field operations.